1. Field of the Invention
The present invention relates to a communication controller, and more particularly to a technique for a communication control system.
2. Description of the Related Art
There has been known a communication control system for an air conditioner in which plural units (for example, outdoor units, indoor units, a remote controller for setting operating environments of these units, etc.) are connected to one another through a pair of control signal lines to transmit/receive communication data among these units through the pair of control signal lines, and also power supply from a unit having a DC power source to a unit having no DC power is carried out through the pair of control signal lines (Japanese Laid-open Patent Application No. Sho-56-155326). According to this type of air conditioner, the pair of control signal lines for connecting the units to one another functions not only as a communication line through which communication data formed of tone burst signals are transmitted/received, but also as a power supply line for supplying power.
Further, in order to avoid occurrence of troubles due to failure of a wiring work or the like, any unit having no DC power source is provided with a circuit for depolarizing the polarity of signals supplied thereto. Accordingly, the non-polarized and bi-directional data communication can be performed while the power supply is carried out from a unit having a DC power source to a unit having no DC power source.
Since the above conventional communication control system uses tone burst signals as communication signals for data communication between units, a high frequency circuit for tone burst signals must be equipped to each unit, and thus the circuit construction is very complicated. In order to solve this problem, a communication controller for an air conditioner that needs no high frequency circuit for tone burst signals has been proposed (Japanese Laid-open Patent Application No. Hei-8-251680).
The communication controller for the air conditioner disclosed in the above publication is shown in FIG. 1.
In this communication controller, a master unit 1 that is connected to the main body 3 of an air conditioner and equipped with a power source and a monitoring controller for controlling the monitoring of the air conditioner is connected to plural slave units 2 through a pair of control signals (communication lines) 4, and each of the master unit 1 and the slave units 2 is equipped with a signal polarity incidence circuit (signal depolarizing circuit) comprising bridged diodes to make the signals of these units coincident in polarity.
The master unit 1 is equipped with a device for superposing an ON/OFF signal (communication signal) having a predetermined amplitude level on a predetermined DC voltage level under the control of the monitoring controller and then transmitting the superposed signal thus obtained to the communication line 4, and also receiving signals from each slave unit 2 through the signal polarity coincidence circuit. Further, each slave unit 2 is equipped with a device for receiving the superposed signal from the master unit through the signal polarity coincidence circuit, separating the superposed signal into the ON/OFF signal having the predetermined amplitude level and the DC voltage having the predetermined level which will be used as a power source for the slave unit concerned, and also transmitting an ON/OFF signal having a predetermined amplitude level under the control of a controller through the signal polarity coincidence circuit to the master unit.
Accordingly, in the communication controller described above, the communication line is also used as the power supply line and the non-polarized and bi-directional communication data can be transmitted/received between the master unit 1 and each slave unit 2 without using any high frequency circuit for tone burst signals while the power supply is carried out from the master unit 1 to each slave unit 2.
In the conventional communication controller disclosed in the Japanese Laid-open Patent Application No. Hei-8-251680, a power supply source having a power source must be determined and fixed in advance (in this case, the master unit is set and fixed as the power supply source). Therefore, when various individual systems are required to be established in accordance with users"" requirements, the system construction and the circuit construction must be changed every time. Further, when the master unit serving as the power supply source is disabled due to some trouble, the power supply to the slave units is stopped and thus the system itself must be stopped. In addition, it is impossible to supply power to the slave units until the master unit is completely repaired or a work of exchanging it with a new one is completed, and this is a critical obstruction to the operation of the system.
Therefore, the present invention has been implemented in view of the foregoing problems of the prior arts, and has an object to provide a communication control system for an air conditioner which enables a system construction satisfying various users"" requirements with a simple circuit construction and in low cost.
Another object of the present invention is to provide a communication control system for an air conditioner in which even when power supply is stopped due to short-circuiting of a communication line, failure of a power supply source or the like, another power supply source is automatically selected and thus the operation of the air conditioning system can be continuously carried out.
In order to attain the above objects, according to the present invention, a communication control system for an air conditioner including at least one outdoor unit, plural indoor units and control equipment such as a remote controller, etc. which are connected to one another through a communication line to mutually carry out data communication through the communication line, is characterized in that at least two indoor units of the plural indoor units are equipped with power supply means, and non-polarized and bi-directional data communication is carried out between the plural indoor units and the control equipment while the power supply means of any one of the at least two indoor units supplies a power source voltage of a main power source to the communication line to the control equipment.
In the communication control system, the power supply means includes a communication superposing unit for superposing communication data on the power source voltage, a switching unit for ON/OFF-controlling the supply of the power source voltage from the main power source to the communication superposing unit, and a polarity coincidence unit for passing therethrough the output of the communication superposing unit to the communication line and depolarizing the power source voltage through the communication line from another indoor unit functioning as a power supply source.
In the communication control system, the communication superposing unit includes a transistor to which ON/OFF signals of communication signals are input, and at least two resistors that are connected to each other in series and divides the power source voltage from the main power source in accordance with the ON/OFF operation of the transistor to superpose the communication signals on the power source voltage.
In the communication control system, the switching unit is disposed between the main power source and the communication superposing unit, and equipped with a transistor for ON/OFF-controlling the supply of the power source voltage from the main power source to the communication superposing unit on the basis of the ON/OFF operation thereof.
In the communication control system, the polarity coincidence unit includes bridged diodes for converting the polarity of signals from the external, and a transistor for bypassing the output signal of the communication superposing unit without passing the output signal through the bridged diodes.
In the communication control system, the power supply unit further includes a voltage detecting unit for detecting the power source voltage in the communication superposing unit.
In the communication control system, the voltage detecting unit includes at least two resistors connected in series, and a transistor connected to the connection point of the two resistors, the power source voltage being applied to one terminal of one of the two resistors at the opposite side to the connection point while one terminal of the other resistors at the opposite side to the connection point is grounded, and the power source voltage being detected on the basis of the ON/OFF operation of the transistor which is switched on/off on the basis of the voltage at the connection point of the two resistors.
In the communication control system, the power supply unit further includes an over-current detecting unit that is disposed between the switching unit and the communication superposing unit and detects the variation of the power source voltage applied to the communication superposing unit to detect short-circuiting of the communication line.
In the communication control system, the over-current detecting unit includes at least one resistor, and a transistor which is switched on/off on the basis of the voltage applied to both the ends of the resistor, a voltage value applied to both the end of the resistor being varied in accordance with the variation of the power source voltage, and the transistor being switched on/off when the voltage value exceeds a predetermined voltage value, thereby detecting the short-circuiting of the communication line.
In the communication control system, the power supply means includes a voltage detecting unit for detecting the power source voltage on the communication line, and a logical unit for judging on the basis of the detection result of the voltage detecting unit whether there is another power supply source which supplies the power source voltage onto the communication line and setting itself to function as a power supply source if it is judged that no other power supply source exists.
In the communication control system, the power supply means includes a detection unit for detecting simultaneous application of a negative-phase power source voltage from another indoor unit functioning as a power supply source onto the communication line or short-circuiting of the communication line, and then stopping the supply of the power source voltage if the simultaneous application of the negative-phase power source voltage from the other indoor unit is detected.
In the communication control system, the power supply means resumes the supply of the power source voltage after the supply of the power source voltage is stopped.
In the communication control system, the power supply means further includes a logical unit for logically judging it on the basis of communication data transmitted through the communication line whether the supply of the power source voltage is stopped or not when another indoor unit functioning as a power supply source supplies an in-phase power source voltage.
In the communication control system, the power supply means of each of the at least two indoor units is equipped with self-selecting means for automatically selecting itself as a power supply source for supplying the power source voltage to the communication line.
According to the present invention, a communication control system including plural first units each having a power supply function of supplying a power source voltage and at least one second unit having no power supply function which are connected to one another through a communication line and through which the power source voltage and communication data are transmitted/received in a non-polarized and bi-directional style through the communication line among the first and second units, is characterized in that each of the first units has a voltage detecting unit for detecting whether the power source voltage exists on the communication line after a main power source is switched on, and a power source voltage judging and supplying unit for making itself function as a power supply source to supply the power source voltage to the communication line if it is judged by the voltage detecting unit that no power source voltage exists on the communication line after a first predetermined time elapses from the switch-on time of the main power source.
In the communication control system, each of the first units further includes a power supply stop unit for stopping the supply of the power supply voltage if it is judged that no power source voltage still exists on the communication line after a second predetermined time longer than the first predetermined time elapses.
According to the present invention, a communication control system for an air conditioner including plural indoor units and at least one outdoor unit, each indoor unit and control equipment containing a remote controller being connected to each other through a communication line, is characterized in that all the indoor units and the control equipment perform non-polarized and bi-directional data communication while a power source voltage is applied from any one of the plural indoor units to the control equipment.